﻿<p><em>IfcEllipseProfileDef</em> defines an ellipse as the profile definition used by the swept surface geometry
or the swept area solid. It is given by its semi axis attributes and placed within the 2D position coordinate system, established by the <em>Position</em> attribute. </p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC2x
</blockquote>

<p>Figure 2 illustrates parameters for the ellipse profile definition. The parameterized profile defines its own position coordinate system.
The underlying coordinate system is defined by the swept surface or swept area solid that uses the profile definition. It is the xy plane of either: </p>
      <ul>
        <li><em>IfcSweptSurface.Position</em></li>
        <li><em>IfcSweptAreaSolid.Position</em></li>
      </ul>
<p>Or in case of sectioned spines it is the xy plane of each list member of <em>IfcSectionedSpine.CrossSectionPositions</em>. By using offsets of the position location, the parameterized profile can be positioned centric (using x,y offsets = 0.), or at any position relative to the profile. Explicit coordinate offsets are used to define cardinal points (for example, upper-left bound). The location of the position coordinate system defines the center of the ellipse. The <em>SemiAxis1</em> attribute defines the first radius of the ellipse in the direction of the X axis, the <em>SemiAxis2</em> attribute defines the second radius of the ellipse in the direction of the Y axis.</p>

<blockquote class="note">
NOTE&nbsp; The semi axes of the ellipse are rectangular to each other by definition.
</blockquote>

<table>
<tr><td><img src="../../../figures/ifcellipseprofiledef-layout1.gif" alt="ellipse profile" border="0" height="300" width="400"></td></tr>
<tr><td><p class="figure">Figure 2 &mdash; Ellipse profile</p></td></tr>
</table>